Method and apparatus for providing bi-directional data services and live television programming to mobile platforms

ABSTRACT

A system for bi-directional data content transfer between a plurality of mobile platforms, such as aircraft or cruise ships, and a ground-based control segment. The system includes the ground-based control segment, a space segment and a mobile system disposed on each mobile platform. The ground-based control segment includes an antenna which is used to transmit encoded RF signals representative of data content to the space segment. The space segment includes a plurality of satellite transponders, with one of the transponders being designated by the ground-based control segment to transpond the encoded RF signals to the mobile system. The mobile system includes steerable receive and transmit antennas. The receive antenna receives the encoded RF signals from the satellite transponder, which are thereafter decoded, demodulated, D/A converted by a communications subsystem and transmitted to a server. The server filters off that data content not requested by any occupants on the mobile system. A local area network (LAN) receives the remaining data content and provides same to individual users on the mobile platform in accordance with previously submitted programming requests or data input by the users at access stations associated independently with each user. The transmit antenna is used to transmit data content from laptop computers, PDAs or other user electronic devices coupled to the access stations back to the designated satellite transponder. The satellite transponder then transponds the data back to the antenna of the ground-based control segment.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/176,570, filed Jul. 5, 2011, now U.S. Pat. No. 8,646,010, which is acontinuation of U.S. patent application Ser. No. 12/272,299, filed Nov.17, 2008, which is a continuation of U.S. patent application Ser. No.09/639,912, filed on Aug. 16, 2000. The entire disclosures of the aboveapplications are incorporated herein by reference.

FIELD

This disclosure relates to worldwide systems for supplying livetelevision programming and bi-directional data services to mobileplatforms, such as aircraft, using satellite communication.

BACKGROUND

Broadband data and video services, on which our society and economy havegrown to depend, have heretofore generally not been readily available tousers on board mobile platforms such as aircraft, ships, trains,automobiles, etc. While the technology exists to deliver such servicesto all forms of mobile platforms, past solutions have been generallyquite expensive, low data rate and/or available to only very limitedmarkets of government/military users and some high-end maritime markets(i.e., cruise ships).

At present, a wide variety of broadcast television (TV) services areavailable to terrestrial users via satellite links. Such servicesinclude commercial Direct Broadcast Satellite (DBS) services (such asDirecTV® and EchoStar®) and custom video, such as rebroadcast video,over private Fixed Satellite Services (FSS) or Broadcast SatelliteServices (BSS) satellites. The data services which can be provided viasatellite link include all conventional Internet services (e.g., email,web browsing, NetMeeting, etc.), as well as virtual private networks(VPNs) for corporate and government customers.

Previously developed systems which have attempted to provide live TV anddata services to mobile platforms have done so with only limitedsuccess. One major obstacle has been the high cost of access to suchbroadband data and video services. Another problem is the limitedcapacity of previously developed systems, which is insufficient formobile platforms carrying dozens, or even hundreds, of individuals whoeach may be simultaneously requesting different channels of programmingor different data services. Furthermore, presently existing systems aregenerally not readily scalable to address the demands of the travelingpublic.

Certain services currently available provide a limited subset of theabove described services. One such service provides a narrow-bandwidthInternet connection to users on a mobile platform. Another serviceprovides either TV broadcast services from available direct broadcastsignals (i.e., EchoStar® and DirectTV®) or provides a custom TVbroadcast signal through dedicated satellite links (i.e., Airshow®).However, no system or method presently exists for providing high speed(i.e., greater than 64 Kbps) data networking services to groups of userson mobile or remote platforms, let alone for providing such high-speednetworking services together with video services.

There are several operational systems that provide limited Internet dataservices on commercial airlines and cruise ships. These systems are verylimited in their link capability (primarily use communication linksdeveloped for telephony) and the service is very expensive (greater thanabout $1.00 per minute for voice connection). For these reasons, and inview of adherent limitations on the capacity of such systems, suchsystems have met with limited commercial success and acceptance.

Current operational systems generally use Inmarsat satellitecommunication links or terrestrial wireless communication links (i.e.,the National Air Telephone System “NATS”) to achieve 2-way connectivityto mobile platforms. These connection forms have several drawbacks:

1) a limited connection bandwidth (typically less than 64 Kbps);

2) limited overall system capacity (due to limited frequency spectrum);and

3) high expense.

Inmarsat operates in the L-band frequency spectrum, where there is verylittle bandwidth and capacity available for providing broadband servicesto the traveling public. NATS based solutions (i.e., GTE Airfone®, AT&TClaircom), familiar to domestic airline travelers who use seatback-mounted telephones, also provide very limited capacity because ofoperation at L-band. These systems also suffer from the additionalproblem that connectivity is only available over land.

Current mobile platform connection methods are inherently narrow bandand restrict the flow of data to the point where common networking tasksare impossible. Typically, this connectivity is achieved through the useof a standard computer telephone modem between the user's computer andthe air-ground or ship-shore telephony system. In this scenario, eachuser gets exclusive use of a full communications channel for theduration of his/her networking session and effectively prevents othersfrom using that portion of the telephony system.

One other service that has received some attention is a service thatprovides pre-stored world-wide-web content to users on a mobileplatform. This service is anticipated to incorporate a server located ona mobile platform to provide its stored content to users on the mobileplatform through a simple touchscreen interface. The content located onthe server would be updated once every few weeks while the mobileplatform is in an inactive mode, such as when an aircraft is parked atan airport gate or a ship is docked at a port. The update of the data onthe mobile platform would be accomplished through the loading of CDROMSor swapping of hard drives on the server. Although the content stored onthe mobile platform with this service can be varied, it will never betimely.

In view of the foregoing, there is a significant need to provide asystem and method for providing live television programming andbi-directional data communication to users onboard mobile platforms viaone or more satellite links. More specifically, there is a need toprovide Internet data communication, Direct Broadcast Satellite Servicesvia BSS satellites, and rebroadcast video of live television programmingvia Ku or Ka-band satellites to a plurality of users onboard one or moremobile platforms, and in a manner which allows each user to request andreceive Internet or other forms of real time data, as well specific liveprogramming which he/she desires to view.

There is also a need to provide a system and method for enablinghundreds or more mobile platforms, such as aircraft, to communicate witha plurality of satellites, where each satellite includes a plurality ofindependent transponders, such that each mobile platform can communicatewith an assigned transponder to permit bi-directional datacommunications by each passenger and viewing by each passenger ofselected live TV programming.

SUMMARY

The present disclosure is directed to a method and apparatus forproviding television and data services to mobile platforms, inaccordance with embodiments of the present disclosure. In oneembodiment, the system of the present disclosure makes use of a groundbased segment for receiving video and data content and transmitting thecontent using radio frequency signals in accordance therewith via aground based antenna to a space segment. The space segment includes asatellite incorporating at least one transponder, and more preferably aplurality of independent transponders, which receives the radiofrequency (RF) signals transmitted from the antenna of the groundsegment and relays these signals to at least one mobile system, and moretypically to a large plurality of mobile systems, using thesatellite-based transponders. Each mobile system is located on a mobileplatform (e.g., aircraft, ship, etc.) and receives the RF signals fromat least one of the satellite transponders and distributes thetransponded video and data content to individual users in accordancewith selections made by the users. Thus, each user only receives thevideo programming and/or data content that he/she specifically selectedor requested.

Optionally, but preferably, the ground-based segment includes at leastone dedicated link to an Internet service provider. One or morededicated links may also be provided to various private/corporateIntranet accounts. A content management center in the ground segment isalso in communication with a network operations center thereof forcontrolling transmission of the live television programming and otherdata to the space segment.

All information sent from the ground station to the mobile platform isbroadcast over the entire coverage region of the satellite transponder.Each satellite is located in a geostationary orbit (GSO) or in anon-geostationary (NGSO) orbit. Packet multiplexing is preferably usedto provide multiple simultaneous access to a plurality of users on eachmobile platform.

The mobile system incorporates a suitable antenna system for effectingbi-directional communications with its assigned transponder. In onepreferred form, the antenna system comprises a steerable antenna carriedby the mobile platform for receiving and transmitting RF signals to andfrom the satellites within the coverage region. The antenna system iscoupled to a receiver which decodes and de-modulates the received RFsignals to produce digital video and audio, as well as data contentsignals. These signals are preferably provided in the form of packets,and fed to a router which filters the packets such that only contentselected/requested by users on the mobile platform is distributed to theusers. In this context users are defined as passengers, cabin crew,cockpit crew, maintenance crew, and non-human entities such asunattended data devices. A distribution system routes the data contentdirectly to the proper users at access stations associated independentlywith each user, or to designated components (such as overhead monitors)located throughout the mobile platform. Thus, each user or occupantreceives only the specific data content (i.e., either data or TVprogramming) that he/she has requested, or the data content can simplybe provided to all passengers on the mobile platform.

The method and apparatus of the present disclosure thus provides theability to conduct bi-directional data communications between aplurality of independent mobile platforms, where each user on eachmobile platform is able to independently request and obtain Internetdata or other forms of data in real time. The present disclosure furtherenables the users to independently request and view selected channels oflive TV programming

BRIEF DESCRIPTION OF DRAWINGS

The various advantages of the present disclosure will become apparent toone skilled in the art by reading the following specification andsubjoined claims and by referencing the following drawings in which:

FIG. 1 is a simplified block diagram drawing illustrating the threemajor components of the system of the present disclosure; and

FIG. 2 is a block diagram of the mobile system carried on each mobileplatform.

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown a system 10 in accordance with anembodiment of the present disclosure for providing data content to andfrom a plurality of moving platforms 12 a-12 f in one or more distinctcoverage regions 14 a and 14 b. The system 10 generally comprises aground segment 16, a plurality of satellites 18 a-18 f forming a spacesegment 17, and a mobile system 20 disposed on each moving platform 12.The moving platforms could comprise aircraft, cruise ships or any othermoving vehicle. Thus, the illustration of the moving platforms 18 asaircraft in the figures herein, and the reference to the mobileplatforms as aircraft throughout the following description should not beconstrued as limiting the applicability of the system 10 to onlyaircraft.

The space segment 17 may include any number of satellites 18 in eachcoverage region 14 a and 14 b needed to provide coverage for eachregion. Satellites 18 a, 18 b, 18 d and 18 e are preferably Ku orKa-band satellites. Satellites 18 c and 18 f are Broadcast SatelliteServices (BSS) satellites. Each of the satellites 18 are further locatedin a geostationary orbit (GSO) or a non-geostationary orbit (NGSO).Examples of possible NGSO orbits that could be used with this disclosureinclude low Earth orbit (LEO), medium Earth orbit (MEO) and highlyelliptical orbit (HEO). Each of the satellites 18 includes at least oneradio frequency (RF) transponder, and more preferably a plurality of RFtransponders. For example satellite 18 a is illustrated having fourtransponders 18 a ₁-18 a ₄. It will be appreciated that each othersatellite 18 illustrated could have a greater or lesser plurality of RFtransponders as required to handle the anticipated number of mobileplatforms 12 operating in the coverage area. The transponders provide“bent-pipe” communications between the aircraft 12 and the groundsegment 16. The frequency bands used for these communication links couldcomprise any radio frequency band from approximately 10 MHz to 100 GHz.The transponders preferably comprise Ku-band transponders in thefrequency band designated by the Federal Communications Commission (FCC)and the International Telecommunications Union (ITU) for fixed satelliteservices FSS or BSS satellites. Also, different types of transpondersmay be employed (i.e., each satellite 18 need not include a plurality ofidentical types of transponders) and each transponder may operate at adifferent frequency. Each of the transponders 18 a ₁-18 a ₄ furtherinclude wide geographic coverage, high effective isotropic radiatedpower (EIRP) and high gain/noise temperature (G/T).

With further reference to FIG. 1, the ground segment 16 includes aground station 22 in bi-directional communication with a content center24 and a network operations center (NOC) 26. A second ground station 22a located in the second coverage area 14 b may be used if more than onedistinct coverage area is required for the service. In this instance,ground station 22 a would also be in bi-directional communication withthe NOC 26 via a terrestrial ground link or any other suitable means forestablishing a communication link with the NOC 26. The ground station 22a would also be in bi-directional communication with a content center 24a. For the purpose of discussion, the system 10 will be described withrespect to the operations occurring in coverage region 14 a. However, itwill be understood that identical operations relative to the satellites18 d-18 f occur in coverage region 14 b. It will also be understood thatthe disclosure may be scaled to any number of coverage regions 14 in themanner just described.

The ground station 22 comprises an antenna and associated antennacontrol electronics needed for transmitting data content to thesatellites 18 a and 18 b. The antenna of the ground station 22 may alsobe used to receive data content transponded by the transponders 18 a₁-18 a ₄ originating from each mobile system 20 of each aircraft 12within the coverage region 14 a. The ground station 22 may be locatedanywhere within the coverage region 14 a. Similarly, ground station 22a, if incorporated, can be located anywhere within the second coveragearea 14 b.

The content center 24 is in communication with a variety of externaldata content providers and controls the transmission of video and datainformation received by it to the ground station 22. Preferably, thecontent center 24 is in contact with an Internet service provider (ISP)30, a video content source 32 and a public switched telephone network(PSTN) 34. Optionally, the content center 24 can also communicate withone or more virtual private networks (VPNs) 36. The ISP 30 providesInternet access to each of the occupants of each aircraft 12. The videocontent source 32 provides live television programming, for example,Cable News Network® (CNN) and ESPN®. The NOC 24 performs traditionalnetwork management, user authentication, accounting, customer serviceand billing tasks. The content center 24 a associated with the groundstation 22 a in the second coverage region 14 b would also preferably bein communication with an ISP 38, a video content provider 40, a PSTN 42,and optionally a VPN 44. An optional air telephone system 28 may also beincluded as an alternative to the satellite return link.

Referring now to FIG. 2, the mobile system 20 disposed on each aircraft18 will be described in greater detail. Each mobile system 20 includes adata content management system in the form of a router/server 50(hereinafter “server”) which is in communication with a communicationssubsystem 52, a control unit and display system 54, and a distributionsystem in the form of a local area network (LAN) 56. Optionally, theserver 50 can also be configured for operation in connection with aNational Air Telephone System (NATS) 58, a crew information servicessystem 60 and/or an in-flight entertainment system (IFE) 62.

The communications subsystem 52 includes a transmitter subsystem 64 anda receiver subsystem 66. The transmitter subsystem 64 includes anencoder 68, a modulator 70 and an Up-converter 72 for encoding,modulating and up-converting data content signals from the server 50 toa transmit antenna 74. The receiver subsystem 66 includes a decoder 76,a demodulator 78 and a down-converter 80 for decoding, demodulating anddown-converting signals received by the receive antenna 82 into basebandvideo and audio signals, as well as data signals. While only onereceiver subsystem 66 is shown, it will be appreciated that preferably aplurality of receiver subsystems 66 will typically be included to enablesimultaneous reception of RF signals from a plurality of RFtransponders. If a plurality of receiver subsystems 66 are shown, then acorresponding plurality of components 76-80 will also be required.

The signals received by the receiver subsystem 66 are then input to theserver 50. A system controller 84 is used to control all subsystems ofthe mobile system 20. The system controller 84, in particular, providessignals to an antenna controller 86 which is used to electronicallysteer the receive antenna 82 to maintain the receive antenna pointed ata particular one of the satellites 18, which will hereinafter bereferred to as the “target” satellite. The transmit antenna 74 is slavedto the receive antenna 82 such that it also tracks the target satellite18. It will be appreciated that some types of mobile antennas maytransmit and receive from the same aperture. In this case the transmitantenna 74 and the receive antenna 82 are combined into a singleantenna.

With further reference to FIG. 2, the local area network (LAN) 56 isused to interface the server 50 to a plurality of access stations 88associated with each seat location on board the aircraft 12 a. Eachaccess station 88 can be used to interface the server 50 directly with auser's laptop computer, personal digital assistant (PDA) or otherpersonal computing device of the user. The access stations 88 could alsoeach comprise a seat back mounted computer/display. The LAN 56 enablesbi-directional communication of data between the user's computing deviceand the server 50 such that each user is able to request a desiredchannel of television programming, access a desired website, accesshis/her email, or perform a wide variety of other tasks independently ofthe other users on board the aircraft 12.

The receive and transmit antennas 82 and 74, respectively, may compriseany form of steerable antenna. In one preferred form, these antennascomprise electronically scanned, phased array antennas. Phased arrayantennas are especially well suited for aviation applications whereaerodynamic drag is important considerations. One particular form ofelectronically scanned, phased array antenna suitable for use with thepresent disclosure is disclosed in U.S. Pat. No. 5,886,671, assigned toThe Boeing Co.

Referring further to FIG. 1, in operation of the system 10, the datacontent is preferably formatted into Internet protocol (IP) packetsbefore being transmitted by either the ground station 22, or from thetransmit antenna 74 of each mobile system 20. For the purpose ofdiscussion, a transmission of data content in the form of IP packetsfrom the ground station 22 will be referred to as a “forward link”transmission. IP packet multiplexing is also preferably employed suchthat data content can be provided simultaneously to each of the aircraft12 operating within the coverage region 14 a using unicast, multicastand broadcast transmissions.

The IP data content packets received by each of the transponders 18 a₁-18 a ₄ are then transponded by the transponders to each aircraft 12operating within the coverage region 14 a. While multiple satellites 18are illustrated over coverage region 14 a, it will be appreciated thatat the present time, a single satellite is capable of providing coverageto an area encompassing the entire continental United States. Thus,depending upon the geographic size of the coverage region and the mobileplatform traffic anticipated within the region, it is possible that onlya single satellite incorporating a single transponder may be needed toprovide coverage for the entire region. Other distinct coverage regionsbesides the continental United States include Europe, South/CentralAmerica, East Asia, Middle East, North Atlantic, etc. It is anticipatedthat in service regions larger than the continental United States, thata plurality of satellites 18 each incorporating one or more transpondersmay be required to provide complete coverage of the region.

The receive antenna 82 and transmit antenna 74 are each preferablydisposed on the top of the fuselage of their associated aircraft 18. Thereceive antenna 74 of each aircraft receives the entire RF transmissionof encoded RF signals representing the IP data content packets from atleast one of the transponders 18 a ₁-18 a ₄. The receive antenna 82receives horizontally polarized (HP) and vertically polarized (VP)signals which are input to at least one of the receivers 66. If morethan one receiver 66 is incorporated, then one will be designated foruse with a particular transponder 18 a ₁-18 a ₄ carried by the targetsatellite 18 to which it is pointed. The receiver 66 decodes,demodulates and down-converts the encoded RF signals to produce videoand audio signals, as well as data signals, that are input to the server50. The server operates to filter off and discard any data content notintended for users on the aircraft 18 and then forwards the remainingdata content via the LAN 56 to the appropriate access stations 88. Inthis manner, each user receives only that portion of the programming orother information previously requested by the user. Accordingly, eachuser is free to request and receive desired channels of programming,access email, access the Internet and perform other data transferoperations independently of all other users on the aircraft 12 a.

An advantage of the present disclosure is that the system 10 is alsocapable of receiving DBS transmissions of live television programming(e.g., news, sports, weather, entertainment, etc.). Examples of DBSservice providers include DirecTV® and Echostar®. DBS transmissionsoccur in a frequency band designated for broadcast satellite services(BSS) and are typically circularly polarized in North America.Therefore, a linear polarization converter may be optionally added toreceive antenna 82 for receiving broadcast satellite services in NorthAmerica. The FSS frequency band that carries the data services and theBSS frequency band that carries DBS transmissions are adjacent to eachother in the Ku-band. In one optional embodiment of the system 10, asingle Ku-band receive antenna can be used to receive either DBStransmissions from DBS satellites 18 c and 18 f in the BSS band or dataservices in the FSS band from one of the FSS satellites 18 a or 18 b, orboth simultaneously using the same receive antenna 82. Simultaneousreception from multiple satellites 18 is accomplished using a multi-beamreceive antenna 82 or by using a single beam receive antenna 82 withsatellites co-located in the same geostationary orbit slot.

Rebroadcast television or customized video services are received andprocessed by the mobile system 20 in exactly the same way. Rebroadcastor customized video content is obtained from the video content source 32and transmitted via the ground station 22 to the FSS satellites 18 a and18 b. The video content is appropriately encoded for transmission by thecontent center 24 before being broadcast by the ground station 22. Somecustomization of the rebroadcast content may occur on the server 50(FIG. 2) of the mobile system 20 to tailor advertisements and otherinformation content to a particular market or interest of the users onthe aircraft 12.

The bulk of data content provided to the users on each aircraft 12 isprovided by using a private portal data content. This is implemented asa set of HTML pages housed on the server 50 of each mobile system 20.The content is kept fresh by periodically sending updated portions froma ground-based server located in content center 24, and in accordancewith a scheduling function controlled by the NOC 26 of the groundsegment 16. The server 50 can readily be configured to accept userlog-on information to support authentication and authorization of usersand to keep track of user and network accounting information to supporta billing system. The authorization and accounting systems can beconfigured to communicate with the ground segment 16 to transferaccumulated data at convenient intervals to the NOC 26.

The system 10 of the present disclosure also provides direct Internetconnectivity via satellite links for a variety of purposes, such as whena user on board the aircraft 12 desires to obtain data content that isnot cached on server 50, or as an avenue for content sources to providefresh content for the private portals. The server may be used to cachethe most frequently requested web pages as well as to host a domain namesystem (DMS) look-up table of the most frequently accessed domains. TheDMS look-up table is preferably maintained by the content center 24 andis periodically updated on the mobile system 20. Refreshing of thecached content of the portal may be accomplished by in-flight, periodic“pushed” cache refresh or at the gate of an airport terminal using anyform of wired or wireless connection to the aircraft 18, or via a manualcache refresh by a crew member of the aircraft 12 carrying on board a CDROM and inserting it into the cache server. The disclosure 10 implementsthe in-flight periodic, pushed cache refresh updates over the satellitelinks. Preferably, refreshing of the cache content occurs during periodsof low demand on the satellite links.

The optional air telephone system 28 can also be employed with thesystem 10 when line-of-sight links to the ground segments 16 areestablished to provide the physical infrastructure. For example, anoptional implementation incorporating an air telephone systems can beused for low data rate return links (2.4 kbps to 9.6 kbps). It will berecognized that other regions, such as Europe and Asia, have similar airtelephone systems that communicate with aircraft using terrestrialcellular communications links. Air telephone systems (e.g., NATS inNorth America) were designed for carrying telephony traffic, but havebeen adapted to pass single user per call, point to point analog modemdata. With the present disclosure, the aggregate return link trafficfrom the mobile system 20 is combined in server/router 50, a switch or aPBX (not shown) and then coupled into the air telephone return link viaan analog modem or directly via a digital interface (e.g., CEPT-E1).Expanded capacity can be provided by establishing multiple simultaneousconnections from the router/switch into the air telephone system.Multi-link, point to point (PPP) data encapsulation can be used toaccomplish the splitting/recombining of the data streams between theairborne and NOC routers. In addition to expanded capacity, thetolerance to a single connection failure is increased with multipleconnections through the air telephone system. The hand-over betweenseparate air telephone system antenna towers is managed by the airtelephone system and the connection between the respective air andground routers is automatically maintained as the mobile platformtraverses multiple coverage areas.

A significant anticipated application of the present disclosure is inconnection with aircraft that fly extended periods of time over waterand remote regions (including polar regions) of the Earth where there islittle or no current satellite transponder coverage. The presentdisclosure can operate with GSO satellites launched in the future intoorbit over oceans, or a new constellation of NGSO satellites to providefull Earth coverage (including the poles).

Referring further to FIG. 1, a transmission of data content from theaircraft 12 a to the ground station 22 will be described. Thistransmission is termed a “return link” transmission. The antennacontroller 86 causes the transmit antenna 74 to maintain the antennabeam thereof pointed at the target satellite 18 a. The channels used forcommunication from each mobile system 20 back to the ground station 22represent point-to-point links that are individually assigned anddynamically managed by the NOC 26 of the ground segment 16. For thesystem 10 to accommodate several hundred or more aircraft 12, multipleaircraft will need to be assigned to each transponder carried by a givensatellite 18. The preferred multiple access methods for the return linkare code division multiple access (CDMA), frequency divisional multipleaccess (FDMA), time division multiple access (TDMA) or combinationsthereof. Thus, multiple mobile systems 20 may be assigned to a singletransponder 18 a ₁-18 a ₄. Where a greater number of aircraft 12incorporating a mobile system 20 are operated within the coverage region14 a, then the number of transponders required increases accordingly.

The receive antenna 82 may implement a closed-loop tracking system forpointing the antenna beam and for adjusting the polarization of theantennas based on receive signal amplitude. The transmit antenna 74 isslaved to the point direction and polarization of the receive antenna82. An alternative implementation could use an open-loop tracking methodwith the pointing direction and polarization determined by knowledge ofmobile platform position and attitude using an on-board inertialreference unit (IRU) and knowledge of the location of the satellites 18.

Encoded RF signals are transmitted from the transmit antenna 74 of themobile system 20 of a given aircraft 12 to an assigned one of thetransponders 18 a ₁-18 a ₄, and transponded by the designatedtransponder to the ground station 22. The ground station 22 communicateswith the content center 24 to determine and provide the appropriate databeing requested by the user (e.g., content from the world wide web,email or information from the user's VPN).

An additional concern that must be taken into account with the system 10is the potential for interference that may result from the smallaperture size of the receive antenna 82. The aperture size of thereceive antenna 82 is typically smaller than conventional “very smallaperture terminal” (VSAT) antennas. Accordingly, the beam from thereceive antenna 82 may encompass adjacent satellites along thegeosynchronous arc. This can result in interference from satellitesother than the target satellite being received by a particular mobilesystem 20. To overcome this potential problem, the system 10 preferablyuses a lower than normal forward link data rate that overcomes theinterference from adjacent satellites. For example, the system 10operates at a preferred forward link data rate of at least about 5 Mbpsper transponder, using a typical FSS Ku-band transponder (e.g.,Telstar-6) and an antenna having an active aperture of about 17 inchesby 24 inches (43.18 cm by 60.96 cm). For comparison purposes, a typicalKu-band transponder usually operates at a data rate of approximately 30Mbps using conventional VSAT antennas.

Using a standard digital video broadcast (DVB) waveform, the forwardlink signal typically occupies less than 8 MHz out of a totaltransponder width of 27 MHz. However, concentrating the transponderpower in less than the full transponder bandwidth could create aregulatory concern. FCC regulations presently regulate the maximumeffective isotropic radiated power (EIRP) spectral density from atransponder to prevent interference between closely spaced satellites.Accordingly, in one embodiment of the present disclosure, spreadspectrum modulation techniques are employed in modulator 70 to “spread”the forward link signal over the transponder bandwidth using well knownsignal spreading techniques. This reduces the spectral density of thetransponded signal, thus eliminating the possibility of interferencebetween two or more mobile systems 20.

It is also equally important that the transmit antenna 74 meetsregulatory requirements that prevent interference to satellites adjacentto the target satellite 18. The transmit antennas used in most mobileapplications also tend to be smaller than conventional VSAT antennas(typically reflector antennas that are 1 meter in diameter). Mobiletransmit antennas used for aeronautical applications should have lowaerodynamic drag, be lightweight, have low power consumption and be ofrelatively small size. For all these reasons, the antenna aperture ofthe transmit antenna 74 is preferably smaller than a conventional VSATantenna. VSAT antennas are sized to create an antenna beam that isnarrow enough to illuminate a single FSS satellite along thegeosynchronous arc. This is important because FSS satellites are spacedat 2° intervals along the geosynchronous arc. The smaller than normalantenna aperture of the transmit antenna 74 used with the presentdisclosure, in some instances, may create an antenna beam that is wideenough to irradiate satellites that are adjacent to the target satellitealong the geosynchronous arc, which could create an interferenceproblem. This potential problem is eliminated by employing spreadspectrum modulation techniques on the return link transmissions as well.The transmitted signal from the transmit antenna 74 is spread infrequency to produce an interfering signal at the adjacent satellitethat is below the threshold EIRP spectral density at which the signalwould interfere. It will be appreciated, however, that spread spectrummodulation techniques may not be required if the angular spacing betweensatellites within a given coverage region is such that interference willnot be a problem.

It will be appreciated that the system 10 of the present disclosureprovides a means for providing bi-directional data content transfer to alarge plurality of independent users on-board a large number of mobileplatforms. The system 10 further enables data content such asrebroadcast video services, broadcast video services and other forms ofdata content to be provided in real time to a large plurality of mobileplatforms such as aircraft, ships or virtually any other form of mobileplatform carrying individuals who desire to access ground-based datacontent sources or to view live television and programming. The systemfurther allows multiple mobile platforms within a given coverage regionto communicate with one or a plurality of transponders within the givencoverage region and to transmit data content via a satellite back to aground-based control system. Accordingly, individual users on-board themobile platform are able to independently access and obtain variousforms of data content as well as selected channels of live televisionprogramming. Importantly, the system 10 of the present disclosure isscalable to accommodate large or small pluralities of mobile platforms,and also scalable over many satellites and coverage regions.

Those skilled in the art can now appreciate from the foregoingdescription that the broad teachings of the present disclosure can beimplemented in a variety of forms. Therefore, while this disclosure hasbeen described in connection with particular examples thereof, the truescope of the disclosure should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, specification and following claims.

What is claimed:
 1. A system for providing data content to a pluralityof mobile platforms via at least one satellite having at least one radiofrequency (RF) transponder, and for transmitting data content from saidmobile platforms via said RF transponder to a ground-based controlcenter: an independent mobile system associated with each said mobileplatform and carried by each said mobile platform; a ground-basedantenna system associated with said ground-based control center fortransmitting encoded RF signals representative of said data content viasaid RF transponder to said mobile system; each said mobile systemcomprising: a steerable transmit antenna and a steerable receiveantenna; a communications subsystem responsive to each of said antennasfor generating baseband video signals and data signals from said encodedRF signals received by said receive antenna, and for producing encodedRF signals from data transmissions input by each of a plurality ofoccupants; a data content management system for filtering of portions ofsaid data content not addressed to occupants on said mobile platform; anetwork for distributing said baseband video signals and said datasignals output from said data content management system to saidoccupants, said network including a plurality of access stations wherebyindividual occupants receive only specific subportions of said basebandvideo signals and said data signals relating to previous informationselections made by said occupants; and said independent mobile systemalso operating to transmit said signals input by each of said occupantsfrom each of said access stations, via said RF transponder, to saidground-based antenna.
 2. The system of claim 1, wherein said accessstations are adapted to be coupled to personal computing devicesoperated by each of said occupants.
 3. The system of claim 1, whereinsaid data content management system comprises a file server.
 4. Thesystem of claim 1, wherein said satellite comprises a plurality of RFtransponders, and wherein said ground based control center designatesone of said transponders to communicate in dedicated fashion with adesignated one of said mobile platforms.
 5. The system of claim 1,wherein said network comprises a local area network.
 6. A system forproviding real time video signals to a mobile receiving platform via asatellite having at least one radio frequency (RF) transponder, thesystem comprising: a ground based system for transmitting RF signalsrepresentative of said video signals to said satellite; a mobilereceiving system disposed on said mobile receiving platform comprising:an antenna for receiving said RF signals from said RF transponder; anantenna control system for use in steering said antenna to track saidsatellite as said mobile receiving platform is in motion; acommunications system responsive to signals received by said antenna forgenerating baseband video signals in accordance therewith; a datacontent management system responsive to said communications system fordetermining which portions of said baseband video signals are to betransmitted to each of a plurality of access stations on said mobilereceiving platform for viewing by individuals on said mobile receivingplatform; and a distribution system for routing said portions of saidbaseband video signals to specific ones of said access stations inresponse to requests by said occupants, such that each said occupantreceives only a portion of said baseband video signals in accordancewith said request made by each said occupant.
 7. The system of claim 6,wherein said communications system comprises a plurality of integratedreceiver/decoders for decoding, demodulating and digital-to-analogconverting received RF signals into said baseband video signals.
 8. Thesystem of claim 6, wherein said data content management system comprisesa server.
 9. The system of claim 6, wherein said baseband video signalsrepresent live television signals.
 10. The system of claim 6, whereinsaid baseband video signals represent direct broadcast televisionsignals.
 11. The system of claim 6, wherein said ground based systemcomprises a network operations center for managing accounting andbilling operations associated with access to the system by each user.12. The system of claim 6, wherein said ground segment operates totransmit encoded data signals to said transponder of said satellite; andwherein said communications system operates to de-modulate and D/Aconvert said RF signals to produce said baseband data signals.
 13. Asystem for supplying a plurality of channels of data content to aplurality of independent mobile receiving platforms, wherein each saidmobile receiving platform has a plurality of occupants, and forreceiving data content transmitted from said mobile receiving platformby said occupants, said system comprising: a ground based antenna fortransmitting encoded radio frequency (RF) signals representing said datacontent; at least one satellite having a plurality of RF transponders inorbit over a desired geographical coverage area within which said mobileplatforms are travelling, for transponding said encoded RF signals; amobile receiving system disposed on each said mobile receiving platform,each said mobile system comprising: an antenna system including areceive antenna for receiving said encoded RF signals from a designatedone of said RF transponders; a transmit antenna for transmitting saiddata content to a designated one of said RF transponders; an antennasystem for steering said transmit and receive antennas to track saidsatellite as said mobile receiving platform is in motion; acommunications system responsive to said encoded RF signals received bysaid receive antenna for demodulating and decoding said encoded RFsignals to produce baseband video signals and data signals; saidcommunications system including a system for transmitting data contentfrom each of said occupants, via said transmit antenna, to saiddesignated one of said transponders; a data content management systemresponsive to said receiver system for determining which portions ofsaid baseband video signals and which portions of said data signals areto be transmitted to specific ones of a plurality of access stations onsaid mobile receiving platform for use by said occupants of said mobilereceiving platform; and a network system for routing said portions ofsaid baseband video signals and said data signals to specific ones ofsaid access stations in response to requests by said occupants, suchthat each said occupant receives only a requested portion of saidbaseband video signals or a requested portion of said data signals. 14.The system of claim 13, wherein said communications system comprises aplurality of integrated receiver/decoders.
 15. The system of claim 13,wherein said data content management system comprises a server.
 16. Thesystem of claim 13, further comprising a data system for supplying crewinformation services to said data content management system.
 17. Thesystem of claim 13, further comprising an air telephone system on boardsaid mobile platform for transmitting data services to at least oneground based voice telephony receiving station within said coveragearea.